BACKGROUND: In July, two major planets ý Venus and Saturn ý will look very close to each other in the night sky. They will be at their closest on June 30th, looking as though they were as near each other as the Moon is wide. This happens because both planets are getting noticeably lower in the sky as they move around in their orbits.
ABOUT VENUS: Venus ý dubbed ýthe jewel of the skyý because it is brighter than the brightest stars ý is often called Earthýs sister planet by astronomers because they are similar in size, mass, density and volume. But the similarities end there. Venus has no oceans and has a heavy atmosphere made up mostly of carbon dioxide. This causes an intense greenhouse effect: sunlight passes through the atmosphere to heat the planetýs surface, but the heat radiating back out is trapped by the carbon dioxide in the atmosphere. So Venus is hotter than Mercury, with a surface temperature of about 900 degrees. The surface of Venus is mostly vast plains covered by lava flows and mountainous regions; there is no liquid water on the surface. The surface is also scarred by impact craters, and there are hundreds of large volcanoes dotted about the surface. Venus rotates once every 243 Earth days, by far the slowest rotation of any of the major planets.
ABOUT SATURN: Saturn has been known since prehistoric times. It is one of the gas giants, and is the sixth planet from the sun, and the second largest in the solar system, exceeded only by Jupiter. Saturn is composed primarily of hydrogen, with smaller amounts of helium and other trace elements. Its interior is made of a small core of rock and ice, surrounded by a thick layer of metallic hydrogen and a gaseous outer later. Saturn is best known for its prominent system of rings, which are mostly comprised of ice particles, rocky debris and dust. Astronomers believe the rings may have been formed from larger moons that were shattered by impacts from comets and meteoroids. The planet also has at least 62 moons; most of them are quite small, but the largest is Titan, which is bigger than the planet mercury and is the only moon in the entire solar system to have a significant atmosphere.
HOW TELESCOPES WORK: A telescope, in its most basic form, is a long tube with a lens on either end that magnifies distant objects. One lens is concave, the other convex, and the light that enters bends, or refracts. The concave lens collects as much light as possible, and a convex lens redirects the rays so that they all converge back to one point. And that point is where you get an image of any object in front of the lens. The reason we have difficulty seeing objects that are far away is they donýt take up sufficient space on the eyeýs retina for the retinal sensor to detect them. A ýbigger eyeý would enable us to collect more light from the object to create a brighter image, and then magnify part of it so that it stretches over more of the retina. A telescope is an extension of the human eye; in this case, it gathers light from dim, distant objects in the sky so we can see them more clearly.
The American Astronomical Society and the American Meteorological Society contributed to the information contained in the TV portion of this report.